LL}  .

When \(L_\mu (x)\)  coincides with the de Rham-Federer current [1]}, [2]}, [3]}, [4]} associated with a link \(\cal L\)  (with support on a Seifert surface [5]} which bounds the link \(\cal L\, \) ), expression () represents precisely the exponent of the linking matrix corresponding to \(\cal L\) . For this reason, in the abelian Chern-Simons theory the Schwinger-Dyson functional provides the solution [6]} for the link observables.
